Electric furnace.



Patented Dec.27,1910.

3 SHEEN-SHEET 2.

Fig; 3-

B. GUTHRIE & J. P. KARGH. ELECTRIC FURNACE.

APPLICATION FILED HA3. 8, 1909. 979,663;

ll fl""' INVENTORS Bayard G'uibrl'e. k/J05? b P K r:/:.

sa a V///////////// /////4 WITNESSES B. GUTHRIE & J. P. KARGH.

ELECTRIC FURNACE. APPLICATION mum MAB. a, 1909.

Patented Dec. 27, 1910.

3 SHEETS-SHEET 3.

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UNITED STATES PATENT OFFICE.

- t I BAYARD GUTHRIE, OF PITTSBURG, PENNSYLVANIA, AND JOSEPH P. KARCH,OF PLAIN- VILLE, CONNECTICUT.

ELECTRIC FURNACE.

Specification of Letters Patent.

Patented Dec. 27, 1910.

To all whom it may concern:

Be it known that we, BAYARD GUTHRIE and JOSEPH P. KARGH, citizens of theUnited States, residing at Pittsburg, Allegheny county, Pennsylvania,and Plainville, 1n the county of Hartford and State of Connecticut, haveinvented certain new and useful Improvements in Electric Furnaces, ofwhich the following is a specification.

This invention relates particularly to the melting of metals by the heatof the electric arc. i

The main object is to provide a simple and reliable construction W iichis efiicient and durable.

It is also desired to facilitate pouring and to produce a clean solidingot without loss of metal.

The complete invention in its preferred form comprises a crucible andfour radially movable electrodes in a tiltable casing which carries aswinging mold. The melting may be carried on in a neutral or reducingatmosphere. i 3

The details will be more clearly understood from the followingspecification and the accompanying three sheets of drawings.

Figure 1 is furnace. Fig. 2 is a plan view of the same with the topremoved and showing a circuit diagram. Fig. 3is an enlarged fragmentaryplan view of one electrode and its operating mechanism. Fig. 4 is a sideview and vertical section of the same. Fig. 5 is an end view and partialsection of the same. Fig. 6 is a vertical section of the furnace showingthe crucible and the casing tilted for pouring. Fig. 7 is an enlargedvertical section of the casing and crucible showing one of thetrunnions. i CuWent.-The crucible ,1, for containing the metal, the fluxand other materials of a charge is, located between the electrodes 2,.3, 4; and 5 which are arranged in pairs and supplied with current fromthe generator 6. This is of the quarter phase alternating .current type.Two direct current machines might be used however if desired.

Uasing.-The shell 7 of the casing is riveted or otherwise secured to thebottom plate 8 and reinforced by the hoop Two brackets such as 10 areriveted or otherwise secured to the bottom and side of the casing andeach carries a trunnion 11. The two trunnions 11, 11 are journaled inthe standa front View of one form of.

Fig.

ards 12, 12. A gear wheel 13 on one of the trunnions meshes with pinion14 and the hand wheel 15 is provided for rotating pinion 14 and thustilting the casing and crucible for pouring. The interior wall and thebottom of the casin is lined with a plastic composition 16 suc as clayand asbestos fiber. A fire brick floor and piers such as 17 are providedto support the crucible be tween the electrodes. A perforated fire claystand 18 is provided when a neutral or reducing atmosphere is desired,the gas being admitted through the pipe 19.

OmcibZe.The crucible is made of a suitable composition such as plumbago,clay and sand in proper proportions and sufiiciently free of oxid ofiron so as to prevent the format-ion of carbid of silicon in theopenation of the furnace so far as possible. The lower or melting partof the crucible is of the usual shape such for instance as is used "inmelting steel. mouth is preferably funnel shaped as at 20 to increaseits capacity and for convenience in filling. The cap 21 fits into thismouth portion and when new sits at the top and gradually sinks lower asit wears away in use. The cover 22 of the casing is held down by staybolts such as 23, 23. A discharge spout or pipe 24, for instance ofplumbago, fits over the outlet lip 25 in the side of the crucible nearthe top and extends out through the wall of the casing. v

zllolcL-From a pair of hooks 26 secured to the top 22 is suspended theingot mold 27 by means of the eye bolts 28, 28. The mold rests on thecross plate 29 and is wedged into the clamps 30, 30; A plumbago funnel31 or phosphorizer is provided at the upper end of the mold. The axis onwhich the mold swings is just in front of the discharge end .of thecrucible spout 24 so that as the crucible is tilted up the stream .ofmetal pouring from the spout always falls straight down into the moldwithout splashing against the cold sides or spilling. This uniform flowinsures a perfectly sound ingot.

Electrodes-Each of the four electrodes is radially movable to and fromthe crucible (see Figs. 3, at and 5). The face of the electrode isshaped to correspondwith the external contour of the crucible, the arcof its horizontal sect-ion being about (see The rear end is dove tailedand fits'vertically into the spring jaws of the The 'ing continued untilthecrucible is empty. The furnace is then returned to its horizonholder32 whose shaft 33 extends through the stufling box or 'land 34 and issecured in the clamp 35. The latter is mounted on a carriage 36 whichslides on the guide bracket 37. -A rotatable screw '38 carried by thisbracket is engaged by the interiorly threaded half nut 39, which issecured to or formed as a part of the carriage 36. By rotating the screw38, for instance by a bandle 40, the nut 39 travels along the screw andmoves the carriage 36, clamp 35 and the holder 32 and its electrode inor out as desired. In order to move all the electrodes simultaneously abevel pinion 41 is mounted on the end of each screw 38 and all of themmesh with the bevel gear wheel 42. This is supported by a grooved wheelor shive 43 adjacent each pinion.-. Rotation ,of any one of the fourscrews and its pinion rotates the big gear and all the other pinions andscrews so that all the electrodes are moved at the same time. Current isled to each electrode for instance by conductors such as 44. The holderis of course insulated properly from the carriage 36 and. from thecasing at the stuffing box 34/ The electrodes and holders are copperedwhere they are in electrical engagement. The glands 34 should of coursebe properly packed to prevent leakage.

Operation-The casing being horizontal as shown in Fig. 1, the crucible1, is charged and the car placed on top and the electrodes 2,3, 4 and 5are all moved up into contact with the crucible. Current is then turnedon and the crucible and its contents are in the circuits. This warms upthe crucible and contents but as the electrodes are purposely made largeand as the crucible and contents are relatively good conductors theheatis not great. The handle 40 is then applied to the end of one of thescrews 38 and the electrodes are slowly withdrawn from contact withthecrucible. Arcs immediately form between the pair of electrodes 2 and3 and the pair t and 5 with the crucible in the center of intense heat.The great heat soon melts the contents of the crucible. The electrodesare then closed into contact with the crucible, the arcs graduallydecrease and the current is turned off. The mold 27 being hung on thehooks 26, 26, the hand wheel 15 is rotated so as to tilt the furnace asshown in Fig. 6 and pour the. contents of the crucible into the mold.The electrodes hold the crucible while pouring. Vhen one mold is filledit can be quickly removed and another substituted and pour tal positionof Fig. 1 and recharged and the operation repeated. I

WVhen it is particularly desired to avoid oxidation of the contents ofthe crucible a neutral orinert gas may be supplied through the pipe 19and which will pass through the perforated stand 18, up around thecrucible 1, and out through the opening in the top of the casingsurrounding the crucible mouth. This will prevent the air from reachingthe contents of the crucible. Similarly a combustible gas may besupplied and burned as it escapes'from the ning in the top of thecasing. This wil have a tendency to withdraw oxy en from the contents ofthe crucible and thus actas a reducin agent.

Each electrode is vertically a justable in the jaws of the holder 32 soas to properly fitthe crucible when moved up to it. Each electrode andits holder is horizontally adjustable in the clan ipl35 inde ndently ofall other electrodes. is enab es the operator to properly adjust theelectrodes so that they will all engage the crucible when it is in thecenter of the casing and so-that when the arcs are formed by-retractingthe electrodes, each electrode will be the same distance from thecrucible as all the others. The carriages and gear connections cause theelectrodes to all move simultaneously and through the same distance andat equal speeds so as to maintain equal arcs on all sides.

Changes in details of construction and substitutions of equivalents areof course contemplated and considered to be within thescope of theclaims hereinafter set forth as will be understood by those familiarwith theart of metal working.

-What We claim is:

1. .In an electric furnace, a tiltable casing, a crucible therein, asupporting said cruci means for retracting said electrodes to form anarc.

2. In an electric furnace, a crucible, a plurality of electrodes havingtheir faces shaped to fit the sides of the crucible and holders and fromthe crucible said. electrodes being vertically removable from saidholder.

3. In an electric furnace, pairs of radially movable 3 ring jaws hav-.ing vertical openings and e ectrodes having wedge sha posterior portionsadapted to be insert in the openings in said jaws and removabletherefrom by vertical movement.

t. In an electric furnace, a crucible having a funnel shaped mouth andan outlet. below the mouth electrodes arranged at the sides of thecrucible and means for tilting said crucible to pour fromsaid outlet.

5. In an electric furnace, a casing, a crucible therein, means forproducing an are, a spout leading from said crucible, a mold swingingfrom the casing and means for tilting the crucible and easing.

6. In an electric furnace, a tiltable casing, a crucible therein, aspout from the crucible leading beyond the edge of the casing, a smallmouthed and relatively deep ingot plurality of electrodes le whenpouring and for said electrodes movable toward a a plurality of 7. In anelectric furnace, a tiltable cas-.

ing, a crucible therein, a spout leading therefrom, a pair of .hookscarried by'the casing, afi'ording an axis immediately in front of theoutlet from said spout and a mold hav- 7 ing eye bolts adapted to behung on said hooks for the purposespecified.

8. In an electric furnace, a casing, a plurality of horizontally movablejaws and a vertically removable electrode carried by each jaw.

9. In an electric furnace, a casing, a mu.

cible therein, a plurality of holders extending through said casing, anelectrode carried by each holder inside said casing and removablevertically therefrom and means outside said casing for moving saidholders.

10. In air electric furnace, a crucible and a plurality of electrodesarranged around the sides of the crucible and each extendingsubstantially from the top to the bottom thereof.

holders therefor, means for radially adjusting the holders'independentlyand means for moving all the holders together.

12. In an electric furnace, a crucible, a plurality of holders, anelectrode vertically insertible in each holder and means for moving saidholders.

13. In an electric furnace, a crucible, a

plurality of holders an elect-rode vertically insertible in each holder,and means for moving said holder radially.

14. In an electric furnace, a crucible, a plurality of independentlyadjustable holders, an electrode vertically insertible in each. holderand means for moving said holders.

15. In an electric furnace, a casing comprising, a shell, a bottomtherefor, a lining therein, a reinforcing hoop about the lower part ofthe shell, trunnion brackets secured to the bottom and shell and meansfor tilting the casing.

In testimony whereof we have afiixed our signatures in presence ofWitnesses.

BAYARD GUTHRIE. JOSEPH P. KARCH. Witnesses for B. Guthrie:

LoUIs MARR, ANDRE SCHMIIT. VVit-nesses for J. P. Karch:

A. V. BROOK, D. G. CLARK.

